JP5179478B2 - Fluorinated surfactant - Google Patents

Description

  The present invention relates to a fluorinated surfactant, an aqueous composition containing the fluorinated surfactant, a method for producing a layered article, and a method for preparing a fluoropolymer dispersion.

  Fluoropolymers, i.e. polymers with fluorinated backbones, have been known for a long time because of several desirable properties such as heat resistance, chemical resistance, weather resistance, UV stability, etc. It has been used for various purposes. Various fluoropolymers are described, for example, in “Modern Fluoropolymers” (editor Jhon Scheirs, Wiley Science, 1997). Commonly known or commercially available fluoropolymers include polytetrafluoroethylene (PTFE), copolymers of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP) (FEP polymers), perfluoroalkoxy copolymers. (PFA), ethylene-tetrafluoroethylene (ETFE) copolymer, terpolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (VDF) (called THV copolymer), and polyvinylidene fluoride polymer (PVDF) Is mentioned. Commercially available fluoropolymers also include fluoroelastomers and thermoplastic fluoropolymers.

  Several methods for producing fluoropolymers are known. These methods include suspension polymerization, aqueous emulsion polymerization, solution polymerization, polymerization in supercritical carbon dioxide, and polymerization in the gas phase. Suspension polymerization and aqueous emulsion polymerization are the most widely used techniques in the industry. Suspension polymerization generally does not use a surfactant and usually results in polymer particles larger than those obtained by aqueous emulsion polymerization.

  Although aqueous emulsion polymerization without the use of various surfactants has been described, there remains a need for fluoropolymer production in an aqueous emulsion polymerization process in the presence of a fluorinated surfactant. A relatively stable fluoropolymer particle dispersion can be obtained in high yield by aqueous emulsion polymerization in the presence of a fluorinated surfactant, and this method is generally considered more environmentally friendly than polymerization in organic solvents. It is done.

  Aqueous emulsion polymerization to obtain a fluoropolymer is often carried out using perfluoroalkanoic acid or a salt thereof as a surfactant. While these surfactants can provide high speed polymerization, good polymerization properties of the resulting fluoropolymer, and good dispersion stability, environmental problems have arisen for these surfactants.

  The present application recognizes the need to find new emulsion polymerization processes that can reduce or avoid the use of perfluoroalkanoic acids and their salts as fluorinated surfactants. The present application recognizes the need for new surfactants, particularly those with less environmental impact.

  Therefore, in some embodiments, the surfactants described herein are less toxic and / or exhibit little or no bioaccumulation. In this context, low toxicity means low acute toxicity in terms of body weight, liver weight, other clinical signs (eg abnormal activity, behavior, and other abnormal central nervous system diseases), and death. Means. Further, in some embodiments, the surfactants described herein have good chemical and thermal stability and can be used in emulsion polymerization in a wide range of conditions (eg, temperature and / or pressure). Can be used. The surfactants described herein also allow for high polymerization rates, good dispersion stability, good fluoropolymer yield, and good polymerization properties. The surfactants described herein can also be recovered from the fluoropolymer dispersion and / or wastewater after aqueous emulsion polymerization utilizing the surfactant.

In another embodiment, the dispersions described herein have good or excellent properties, such as, for example, good film forming ability, in coating applications and / or substrate impregnation.
In some embodiments, the aqueous emulsion polymerization described herein can be performed in a convenient and cost effective manner using equipment commonly used in aqueous emulsion polymerization of fluorinated monomers.

In one aspect, the present invention provides
a) The following general formula:
[R _f ¹ —O— (CF ₂ ) _n —CO ₂ ⁻ ] _i M ^{i +}
Wherein R _f ¹ is CF ₃ CFH, n is an integer selected from 1, 2, 5, and 6, M is a cation having a valence i, and i is 1, 2, And a partially fluorinated surfactant having
b) The following general formula:
[R _f ² —O— (CF ₂ ) _m —CO ₂ ⁻ ] _i M ^{i +}
Wherein R _f ² is CF ₃ CF ₂ , m is an integer selected from 1, 3, 4, and 6, M is a cation having a valence i, and i is 1, 2 And a fully fluorinated ethyl ether surfactant having a selected from
c) The following general formula:
[R _f ³ —O— (CF ₂ ) _p —CO ₂ ⁻ ] _i M ^{i +}
Wherein R _f ³ is CF ₃ (CF ₂ ) ₃ , p is an integer selected from 1, 4, and 6, M is a cation having a valence i, and i is 1, And a fluorinated ether carboxylic acid or acid derivative selected from: a fully fluorinated butyl ether surfactant having a selected from 2 and 3. Examples of cations M ^{i +} include ammonium ions such as H ⁺ , NH ₄ ⁺ or tetraalkylammonium ions, alkali metal ions including sodium, potassium, lithium, and metals such as alkaline earth cations such as calcium and magnesium. And cations. Preferred cations are H ⁺ and ammonium.

In another aspect, the invention provides:
a) The following general formula:
[R _f ¹ —O— (CF ₂ ) _n —CO ₂ ⁻ ] _i M ^{i +}
Wherein R _f ¹ is CF ₃ CFH, n is an integer selected from 1 to 6, M is a cation having a valence i, and i is selected from 1, 2, and 3. A partially fluorinated surfactant having
b) The following general formula:
[R _f ² —O— (CF ₂ ) _m —CO ₂ ⁻ ] _i M ^{i +}
Wherein R _f ² is CF ₃ CF ₂ , m is an integer selected from 1, 3, 4, 5, and 6, M is a cation having a valence i, and i is 1 A fully fluorinated ethyl ether surfactant having (selected from 2 and 3);
c) The following general formula:
[R _f ³ —O— (CF ₂ ) _p —CO ₂ ⁻ ] _i M ^{i +} (wherein R _f ³ is CF ₃ (CF ₂ ) ₃ and p is selected from 1, 4, and 6). A fluorinated surfactant selected from: a fully fluorinated butyl ether surfactant having an integer, M is a cation having a valence i, and i is selected from 1, 2, and 3) The present invention relates to an aqueous composition containing an agent. Examples of cations M ^{i +} include ammonium cations such as H ⁺ , NH ₄ ⁺ or tetraalkylammonium ions, alkali metal ions including sodium and potassium, and metal cations such as alkaline earth cations such as calcium and magnesium. Can be mentioned.

In yet another aspect, the invention relates to a process for preparing a fluoropolymer dispersion comprising the step of polymerizing one or more fluorinated monomers in an aqueous emulsion, the polymerization step comprising:
a) The following general formula:
^{_{[R f 1 -O- (CF 2}} ) n -CO 2] i M i + (A)
Wherein R _f ¹ is CF ₃ CFH, n is an integer selected from 1 to 6, M is a cation having a valence i, and i is selected from 1, 2, and 3. A partially fluorinated surfactant having
b) The following general formula:
^{_{[R f 2 -O- (CF 2}} ) m -CO 2 -] i M i + (B)
Wherein R _f ² is CF ₃ CF ₂ , m is an integer selected from 1, 3, 4, 5, and 6, M is a cation having a valence i, and i is 1 A fully fluorinated ethyl ether surfactant having (selected from 2 and 3);
c) The following general formula:
[R _f ³ —O— (CF ₂ ) _p —CO ₂ ⁻ ] _i M ^{i +} (C)
Wherein R _f ³ is CF ₃ (CF ₂ ) ₃ , p is an integer selected from 1, 4, and 6, M is a cation having a valence i, and i is 1, Carried out in the presence of one or more fluorinated surfactants selected from: a fully fluorinated butyl ether surfactant having a selected from 2 and 3. Examples of cations M ^{i +} include ammonium cations such as H ⁺ , NH ₄ ⁺ or tetraalkylammonium ions, alkali metal ions including sodium and potassium, and metal cations such as alkaline earth cations such as calcium and magnesium. Can be mentioned.

  The surfactants described herein have been found to be suitable for aqueous emulsion polymerization of monomers, particularly fluorinated monomers. In addition to use in aqueous emulsion polymerization, fluorinated surfactants are useful for other applications, such as used in coating compositions or in stabilizing dispersions including, for example, fluoropolymer dispersions. .

ＣＨ₃ＯＣＯ（ＣＨ₂）_nＣＯＯＣＨ₃＋ＥＣＦまたはＤＦ→ＦＣＯ（ＣＦ₂）_nＣＯＦ
（式中、反応（Ｉ）の目的において、ｎを任意の整数、例えば１〜６とすることができる）ＥＣＦの一般的な手順は、例えば、米国特許第２，７１３，５９３号、及びＰＣＴ国際公開特許ＷＯ９８／５０６０３号に記載される。ＤＦの一般的な手順は、例えば、米国特許第５，４８８，１４２号に記載される。 It has been found that the surfactants described herein can be easily and conveniently prepared in a cost effective manner. For example, the general formula:
[R _f ¹ —O— (CF ₂ ) _n —CO ₂ ⁻ ] _i M ^{i +}
Wherein R _f ¹ is CF ₃ CFH, n is an integer selected from 1, 2, 5, and 6, M is a cation having a valence i, and i is 1, 2, In the preparation of a partially fluorinated surfactant having a selected from (1) and (3), the organic molecule can be first fluorinated as disclosed in reaction scheme (I) below. Fluorination can be either electrolytic fluorination (ECF) or direct fluorination (DF). For example, the following fluorination reaction is performed according to reaction (I).

CH ₃ OCO (CH ₂ ) _n COOCH ₃ + ECF or DF → FCO (CF ₂ ) _n COF
(For purposes of reaction (I), n can be any integer, such as 1-6) General ECF procedures are described, for example, in US Pat. No. 2,713,593, and PCT It is described in international publication patent WO98 / 50603. The general procedure for DF is described, for example, in US Pat. No. 5,488,142.

As another method, a hexafluoropropylene oxide coupling reaction may be included in the first step. For example, according to reaction (II).

The dibasic acid fluoride formed in reaction (II) can then be converted to a partially fluorinated surfactant by decarboxylation with a base in the presence of water. This can generally be shown by reaction (III).
FCOCF (CF ₃ ) —O— (CF ₂ ) _{n + 1} C (O) F + H ₂ O + (base) → CF ₃ —CHF—O— (CF ₂ ) _{n + 1} CO ₂ M
(Wherein the base can be a metal hydroxide or a carbonate, and M is a metal cation such as alkali metal ions including sodium and potassium, and alkaline earth cations such as calcium and magnesium)

In some embodiments, the partially fluorinated surfactant of the present invention has the general formula:
[R _f ¹ —O— (CF ₂ ) _n —CO ₂ ⁻ ] _i M ^{i +}
Wherein R _f ¹ is CF ₃ CFH, n is an integer selected from 1, 2, 5, and 6, M is a cation having a valence i, and i is 1, 2, And 3). In some embodiments, n is selected from 1 and 2. In another embodiment, n is selected from 5 and 6.

Specific examples of partially fluorinated surfactants include:
CF ₃ CFH—O—CF ₂ CO ₂ H,
_{CF 3 CFH-O- (CF2)} 2 CO 2 H,
_{CF 3 CFH-O- (CF 2} ) 3 CO 2 H,
CF ₃ CFH—O— (CF ₂ ) ₄ CO ₂ H,
_{CF 3 CFH-O- (CF 2} ) 5 CO 2 H,
_{CF 3 CFH-O- (CF 2} ) 6 CO 2 H and the like.

In another embodiment, the following general formula:
[R _f ² —O— (CF ₂ ) _m —CO ₂ ⁻ ] _i M ^{i +}
Wherein R _f ² is CF ₃ CF ₂ , m is an integer selected from 1, 3, 4, and 6, M is a cation having a valence i, and i is 1, 2 And a perfluorinated ethyl ether surfactant having the following general formula:
[R _f ³ —O— (CF ₂ ) _p —CO ₂ ⁻ ] _i M ^{i +}
Wherein R _f ³ is CF ₃ (CF ₂ ) ₃ , p is an integer selected from 1, 4, and 6, M is a cation having a valence i, and i is 1, Fully fluorinated butyl ether surfactants having (selected from 2 and 3) may each be prepared by a suitable synthetic route. First, for example, an acid fluoride may be prepared by reacting an ether precursor with SbF ₅ in oxygen.
_{R f -O- (CF 2) x} CF = CF 2 + SbF 5 (O 2) → R f -O- (CF 2) x + 1 -COF + H 2 O → R f -O- (CF 2) x + 1 -COOH
(Wherein, R _f is CF ₃ CF ₂ or CF ₃ (CF _{2) 3,} x is 0-5, preferably x is 0) One skilled in the art, various R _f values, and It will be appreciated that this synthetic route of preparation producing x-value carboxylic ethers is generally applicable.

Other generally applicable synthetic routes that provide the fully fluorinated ethyl ether surfactants and fully fluorinated butyl ether surfactants of the present invention include the following reaction sequence.
R ′ _f —COF + KF + Br (CH ₂ ) _n —CO ₂ R → R ′ _f CF ₂ —O— (CH ₂ ) _n —CO ₂ R
(Wherein R ′ _f is CF ₃ or CF ₃ (CF ₂ ) ₂ and n is, for example, 1 to 6) the resulting partially hydrogenated ester may be subsequently fluorinated. Can be produced after hydrolysis.
R ′ _f CF ₂ —O— (CH ₂ ) _n —CO (R) + (1) F ₂ ; (2) Hydrolysis → R ′ _f CF ₂ —O— (CF ₂ ) _n —CO ₂ H
Wherein R is selected from halogens containing fluorine and alkoxy groups containing linear, branched, or cyclic alkoxy groups, where the alkoxy groups may be unfluorinated or partially May be fluorinated)

In some embodiments, the fully fluorinated ethyl ether surfactant has the general formula:
[R _f ² —O— (CF ₂ ) _m —CO ₂ ⁻ ] _i M ^{i +}
Wherein R _f ² is CF ₃ CF ₂ , m is an integer selected from 1, 3, 4, and 6, M is a cation having a valence i, and i is 1, 2 , And 3). In certain embodiments, m is selected from 3, 4, and 6.

Specific examples of fully fluorinated ethyl ether surfactants include:
CF ₃ CF ₂ —O—CF ₂ CO ₂ H,
_{CF 3 CF 2 -O- (CF2)} 2 CO 2 H,
_{CF 3 CF 2 -O- (CF 2} ) 3 CO 2 H,
_{CF 3 CF 2 -O- (CF 2} ) 4 CO 2 H,
_{CF 3 CF 2 -O- (CF 2} ) 5 CO 2 H,
_{CF 3 CF 2 -O- (CF 2} ) 6 CO 2 H and the like.

The fully fluorinated butyl ether surfactant, in some embodiments, has the general formula:
[R _f ³ —O— (CF ₂ ) _p —CO ₂ ⁻ ] _i M ^{i +}
Wherein R _f ³ is CF ₃ (CF ₂ ) ₃ , p is an integer selected from 1, 4, and 6, M is a cation having a valence i, and i is 1, 2 and 3). In certain embodiments, p is selected from 4 and 6.

Specific examples of fully fluorinated butyl ether surfactants include:
CF ₃ (CF ₂ ) ₃ —O—CF ₂ CO ₂ H,
_{CF 3 (CF 2) 3 -O-} (CF2) 2 CO 2 H,
CF ₃ (CF ₂ ) ₃ —O— (CF ₂ ) ₃ CO ₂ H,
_{CF 3 (CF 2) 3 -O-} (CF 2) 4 CO 2 H,
_{CF 3 (CF 2) 3 -O-} (CF 2) 5 CO 2 H,
_{CF 3 (CF 2) 3 -O-} (CF 2) 6 CO 2 H and the like.

  In some embodiments, the partially fluorinated surfactant, the fully fluorinated ethyl ether surfactant, and the fully fluorinated butyl ether surfactant described herein are in a preferred environment. Show properties. For example, in some embodiments, surfactants have a low potential for bioaccumulation and are readily excreted from mammals, as illustrated by the renal elimination half-life of surfactants in male rats. The half-life can be 35 hours or less, 30 hours or less, 24 hours or less, or even 12 hours or less in some embodiments. In another embodiment, the surfactants described herein are not metabolically degraded. Furthermore, these surfactants can reduce the potential for mammalian bioaccumulation, as exemplified by the recovery of surfactant by excretion from the kidney 96 hours after administration in male rats. The recovery can in some embodiments be 30% or higher, 45% or higher, 50% or higher, 75% or higher, or even 90% or higher. In general, fluorinated carboxylic acids in which the fluorinated aliphatic moieties in the compound each have 3 or fewer carbon atoms satisfy the aforementioned conditions for recovery and half-life.

The present invention also provides a method for preparing fluoropolymer dispersions. The method includes a polymerization step of one or more fluorinated monomers in an aqueous emulsion. In one embodiment, the following general formula:
^{_{[R f 1 -O- (CF 2}} ) n -CO 2] i M i +
Wherein R _f ¹ is CF ₃ CFH, n is an integer selected from 1 to 6, M is a cation having a valence i, and i is selected from 1, 2, and 3. The polymerization may be carried out in the presence of one or more partially fluorinated surfactants having In another embodiment, the following general formula:
[R _f ² —O— (CF ₂ ) _m —CO ₂ ⁻ ] _i M ^{i +}
Wherein R _f ² is CF ₃ CF ₂ , m is an integer selected from 1, 3, 4, 5, and 6, M is a cation having a valence i, and i is 1 The polymerization may be carried out in the presence of a fully fluorinated ethyl ether surfactant having (selected from 2, and 3). In yet another embodiment, the following general formula:
[R _f ³ —O— (CF ₂ ) _p —CO ₂ ⁻ ] _i M ^{i +}
Wherein R _f ³ is CF ₃ (CF ₂ ) ₃ , p is an integer selected from 1, 4, and 6, M is a cation having a valence i, and i is 1, The polymerization may be carried out in the presence of a fully fluorinated butyl ether surfactant having (selected from 2 and 3). This process may also be performed in the presence of any mixture of the fluorinated surfactants described above.
In certain embodiments, one or more fluorinated surfactants of formula (I) are used in aqueous emulsion polymerization of one or more fluorinated monomers, particularly gaseous fluorinated monomers. By gaseous fluorinated monomer is meant a monomer that exists as a gas under polymerization conditions. The polymerization of the fluorinated monomer may be initiated in the presence of a fluorinated surfactant according to formulas (A) to (C). That is, the polymerization is initiated in the presence of a fluorinated surfactant. The amount of fluorinated surfactant used may vary depending on the desired properties such as the amount of solids and particle size. Generally, the amount of fluorinated surfactant is from 0.001% to 5% by weight, for example from 0.005% to 2% by weight, based on the weight of water during polymerization. A practical range is 0.05% to 1% by weight. The polymerization is generally initiated in the presence of a fluorinated surfactant and does not exclude the addition of additional fluorinated surfactant during the polymerization, although this is generally not necessary. Nevertheless, it may be desirable to add certain monomers to the polymerization in the form of an aqueous emulsion. For example, fluorinated monomers, and especially fully fluorinated comonomers that are liquid under polymerization conditions, are advantageously added in the form of an aqueous emulsion (which may be a microemulsion). Such comonomer emulsions can be prepared using the fluorinated surfactants according to the above formulas (A) to (C) as emulsifiers.

  Furthermore, the aqueous dispersion may further contain one or more fluorinated surfactants in addition to the fluorinated surfactant described above. Examples of other fluorinated surfactants include perfluoroalkyl carboxylic acids. Other possible fluorinated surfactants are perfluoropolyether surfactants. In further additional embodiments, the aqueous dispersion may further comprise one or more non-fluorinated surfactants.

  Aqueous emulsion polymerization is carried out at a temperature of 10 to 150 ° C., preferably 20 ° C. to 110 ° C. and typically at a pressure of 200 kPa (2 bar) to 3000 kPa (30 bar), in particular 500 kPa (5 bar) to 2000 kPa (20 bar). It can be carried out. The reaction temperature may be varied during the polymerization to influence the molecular weight distribution, ie to obtain a broad molecular weight distribution or to obtain a bimodal or multimodal molecular weight distribution.

  The pH of the polymerization medium may be in the range of pH 2-11, preferably 3-10, most preferably 4-10.

  Aqueous emulsion polymerization is usually initiated by an initiator that includes any initiator known to initiate free radical polymerization of the fluorinated monomer. Suitable reaction initiators include peroxides and azo compounds and redox initiators. Specific examples of peroxide initiators include hydrogen peroxide, sodium peroxide or barium, for example, diacyl peroxides such as diacetyl peroxide, disuccinyl peroxide, dipropionyl peroxide, dibutyryl peroxide, dibenzoyl peroxide, benzoyl acetyl peroxide, Diglutaric acid peroxide and dilauryl peroxide and further peracids and their salts such as ammonium salts, sodium salts, potassium salts and the like are mentioned. An example of a peracid is peracetic acid. Esters of peracids can be used as well, and examples thereof include tert. Butyl peroxyacetate, and tert. -Butyl peroxypivalate is mentioned. Examples of the inorganic substance include persulfuric acid, permanganic acid, or ammonium salt, alkali salt or alkaline earth salt of manganic acid or manganic acid. Persulfate initiators such as ammonium persulfate (APS) can be used alone or in combination with a reducing agent. Suitable reducing agents include, for example, bisulfites such as ammonium bisulfite or sodium metabisulfite, thiosulfates such as ammonium thiosulfate, potassium or sodium, hydrazine, azodicarboxylates, and azodicarboxyldiamides. (ADA). Other reducing agents that may be used include sodium formaldehyde sulfoxylate (Rongalit®) or fluoroalkylsulfinates as described in US Pat. No. 5,285,002. It is done. The reducing agent typically shortens the half-life of the persulfate initiator. In addition, metal salt catalysts such as copper, iron or silver salts may be added. The amount of initiator may be from 0.01% to 1% by weight (based on the fluoropolymer solid to be produced). In one embodiment, the amount of initiator is 0.05% to 0.5% by weight. In another embodiment, this amount may be from 0.05% to 0.3% by weight.

The aqueous emulsion polymerization system may further comprise other agents such as buffering agents and, optionally, complexing agents or chain transfer agents. Examples of chain transfer agents that can be used include dimethyl ether, methyl t-butyl ether, alkanes having 1 to 5 carbon atoms, such as ethane, propane, and n-pentane, halogenated hydrocarbons, such as CCl ₄ , CHCl. ₃ and CH ₂ Cl ₂ , and hydrofluorocarbon compounds such as CH ₂ F—CF ₃ (R134a). In addition, esters such as ethyl acetate and malonic esters are also applicable.
Examples of fluorinated monomers that may be polymerized using the fluorinated surfactant of formula (I) as an emulsifier include partially or fully fluorinated gaseous monomers including fluorinated olefins, For example, tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), vinyl fluoride (VF), vinylidene fluoride (VDF), partially or fully fluorinated allyl ether, As well as partially or fully fluorinated vinyl ethers. The polymerization may further involve non-fluorinated monomers such as ethylene and propylene.

Other examples of fluorinated monomers that may be used in the aqueous emulsion polymerization according to the present invention include:
Includes those corresponding to CF ₂ = CF—O—R _f .
(Wherein R _f represents a fully fluorinated aliphatic group that may contain one or more oxygen atoms). Preferably, the perfluorovinyl ethers have the general formula:
CF ₂ = CFO (R _f O) _n (R ′ _f O) _m R ″ _f
Wherein R _f and R ′ _f are different linear or molecular perfluoroalkylene groups of 2 to 6 carbon atoms, m and n are independently 0 to 10, and R ″ _f is Examples of perfluorovinyl ethers of the above formula include perfluoro-2-propoxypropyl vinyl ether (PPVE-2), perfluoro-3-methoxy-n-, which are perfluoroalkyl groups of 1 to 6 carbon atoms. propyl vinyl ether, perfluoro-2-methoxy - ethyl vinyl ether, perfluoromethyl vinyl ether (PMVE), perfluoro -n- propyl vinyl ether (PPVE-1), and _{CF 3 - (CF 2) 2} -O-CF (CF 3) -CF _{2 -O-CF (CF 3)} -CF 2 -O-CF = CF 2, and the like.

Examples of fluorinated allyl ethers that can be used include the following general formula:
CF ₂ = CF—CF ₂ —O—R _f
(Wherein R _f represents a fully fluorinated aliphatic group that may contain one or more oxygen atoms).

Still further, the polymerization may involve, for example, a comonomer having a functional group such as a group that can participate in a peroxide curing reaction. Such functional groups include halogens such as Br or I, and nitrile groups. Specific examples of such comonomers that may be listed herein include the following:
(A) Bromo- or iodo- (per) fluoroalkyl- (per) fluorovinyl ether of the formula: Z—R _f —O—CX═CX ₂
Wherein each X may be the same or different and represents H or F, Z is Br or I, R _f is (per) fluoroalkylene C ₁ -C ₁₂ , optionally containing chlorine and / or ether oxygen atoms; for _{example, BrCF 2 -O-CF = CF} 2, BrCF 2 CF 2 -O-CF = CF 2, BrCF 2 CF 2 CF 2 -O-CF = CF 2, CF _{3 CFBrCF 2 -O-CF = CF} 2 , etc.) and (b) bromo, such as those having the formula - or iodo-containing fluoroolefins:
Z ′ − (R _f ′) _r −CX = CX ₂ ,
Wherein X independently represents H or F, Z ′ is Br or I, R _f ′ is perfluoroalkylene C ₁ -C ₁₂ and optionally contains a chlorine atom, and r is 0 or 1) For example: bromotrifluoroethylene, 4-bromo-perfluorobutene-1, etc .; or bromofluoroolefins such as 1-bromo-2,2-difluoroethylene, and 4 -Bromo-3,3,4,4-tetrafluorobutene-1.

Examples of nitrile-containing monomers that may be used include:
CF ₂ = CF—CF ₂ —O—R _f —CN
CF ₂ = CFO (CF ₂ ) _L CN
_{CF 2 = CFO [CF 2 CF} (CF 3) O] g (CF 2) v OCF (CF 3) CN
CF ₂ = CF [OCF ₂ CF (CF ₃ )] _k O (CF ₂ ) _u CN
(Wherein L represents an integer of 2 to 12; g represents an integer of 0 to 4; k represents 1 or 2; v represents an integer of 0 to 6; u represents an integer of 1 to 6) And R _f is a perfluoroalkylene or divalent perfluoroether group). Specific examples of the nitrile containing liquid fluorinated monomers include perfluoro _{(8-cyano-5-methyl-3,6-dioxa-1-octene), CF 2 = CFO (CF} 2) 5 CN, and CF ₂ = CFO _{(CF 2) 3 OCF (CF} 3) CN , and the like.

  Aqueous emulsion polymerization can be used to produce a variety of fluoropolymers, including perfluoropolymers with fully fluorinated backbones as well as partially fluorinated fluoropolymers. Aqueous emulsion polymerization can also result in melt processable fluoropolymers and those that are not melt processable, such as, for example, polytetrafluoroethylene and so-called modified polytetrafluoroethylene. The polymerization process can also produce fluoroelastomers as well as fluoropolymers that can be cured to produce fluorothermoplasts. Fluorothermoplasts are generally fluoropolymers that have a distinct and very pronounced melting point, typically in the range of 60-320 ° C or 100-320 ° C. They thus have a substantially crystalline phase. Since fluoropolymers used to make fluoroelastomers are typically amorphous and / or have negligible amounts of crystallinity, these fluoropolymers have no or little melting point. I can't.

  Aqueous emulsion polymerization results in a dispersion of the fluoropolymer in water. Generally, the amount of fluoropolymer solids in the dispersion that results directly from polymerization varies between 3% and 40% by weight, depending on the polymerization conditions. A typical range is 5-30% by weight, for example 10-25% by weight. The particle size (volume average particle size) of the fluoropolymer is typically 40 nm to 400 nm, and the typical particle size is 60 nm to 350 nm. The total amount of fluorinated surfactant described in formula (I) in the resulting dispersion is typically 0.001 to 5% by weight, based on the amount of fluoropolymer solids in the dispersion. A typical amount may be 0.01-2% or 0.02-1% by weight.

  According to certain embodiments, the fluoropolymer is separated from the aqueous dispersion, for example by suspecting. After such suspecting, the majority of the fluorinated surfactant often remains on the fluoropolymer. When the fluoropolymer is heated for drying purposes, the fluorinated surfactant volatilizes and is carried away into the dryer or oven exhaust. In order to avoid release of the fluorinated carboxylic acid into the environment, the exhaust can be contacted with, for example, a cleaning solution or cleaning liquid, and the fluorinated surfactant can be recovered from the exhaust stream (also referred to as the exhaust gas stream).

  Recovering the fluorinated surfactant from the exhaust stream and reusing the surfactant in the emulsion polymerization of the fluorinated monomer provides economic and environmental benefits. Accordingly, in another embodiment, the present invention provides a process for recovering a fluorinated surfactant described in the present invention from an exhaust stream, the process comprising removing the exhaust stream and the fluorinated surfactant from the exhaust stream. Contacting with a composition that can be at least partially removed.

  The process described as recovery of fluorinated surfactant allows recovery of the “carboxylic acid” of the fluorinated surfactant. For convenience, the term “fluorinated carboxylic acid” may be used to mean the free acids as well as their salts. The fluorinated surfactant used in the recovery process may be any fluorinated surfactant described in this application.

  In accordance with the present invention, the exhaust stream containing the fluorinated surfactant can be contacted with a composition that can at least partially remove the fluorinated surfactant from the exhaust stream. For convenience, a composition capable of at least partially removing the fluorinated surfactant will be referred to hereinafter as a “cleaning composition”.

  According to one embodiment, the cleaning composition is a cleaning liquid. Usually, the exhaust is brought into contact with the cleaning liquid at a temperature at which the solubility of the fluorinated surfactant in the cleaning liquid is maximized. A typical temperature may range from 10 ° C to 80 ° C. Examples of the cleaning liquid include aqueous liquids such as demineralized water and aqueous alkaline solutions, and organic solvents such as glycol ether solvents. Suitable aqueous alkaline solutions include diluted alkaline solutions and high density alkaline solutions. The latter can separate the fluorinated surfactant as a separate phase, so that the fluorinated surfactant can be easily recovered and reused.

In certain embodiments, the density of the alkaline cleaning solution is set to the density of the precipitated salt of the fluorinated surfactant so that the fluorinated surfactant is separated and discharged as the upper phase of the high density cleaning solution in the precipitation vessel. Set to a higher value. The cleaning solution may be removed at the bottom and returned directly to the cleaning process. The density of the alkaline cleaning solution, the temperature in the washing apparatus, generally greater than 1.15 g / cm ^3, will preferably exceed 1.3 g / cm ^3.

Typically, the alkaline compound chosen is an alkali metal hydroxide, preferably a potassium hydroxide solution, and especially a sodium hydroxide solution, at a concentration such that the density is greater than 1.15 g / cm ³ . For potassium hydroxide solutions, the concentration is generally greater than 16%, and for sodium hydroxide solutions, the concentration is generally greater than 14%. It can also be a mixture of different alkalis.

If a lower concentration of alkali metal hydroxide is desired, a salt can be added to achieve a cleaning solution density of at least 1.15 g / cm ³ . Available salts are very common inorganic compounds that do not form poorly soluble hydroxides in an alkaline environment. These are in particular alkali metal salts such as sodium or potassium chloride, bromide or sulfate. However, when a metal is used as the material for the processing apparatus, chloride ions can cause corrosion, so other salts, such as sulfates, are generally preferred for setting the density of the cleaning solution. Advantageously, a salt having the same cation as the alkaline compound is selected, so when sodium hydroxide solution is used, sodium sulfate is preferred. It can also be a mixture of salts. A lighter upper phase containing a highly fluorinated carboxylate results in a salt paste with an alkaline aqueous medium (ie, including alkali metal hydroxide and, where appropriate, added salt) attached .

In certain embodiments, a potassium carbonate solution having a density of at least 1.15 g / cm ³ is used as the cleaning composition. For example, the density may be 1.2 to 1.4 g / cm ³ . When collecting the separated upper phase, for example in a tank, it is generally observed that highly fluorinated carboxylates are more concentrated by forming at least two phases again after standing for several hours. Analysis identifies the phase that contains the salt of the fluorinated surfactant and preferably other phases that are returned to the process.

  In some embodiments, an aqueous alkali hydroxide solution containing an alkali hydroxide at a concentration of 0.01 to 10% by weight, such as sodium hydroxide or potassium hydroxide solution, is used.

  In another embodiment, demineralized water is used as the wash solution. In this case, the cleaning solution is preferably recirculated until the fluorinated surfactant concentration reaches 500 to 5000 parts per million (ppm), more preferably 1000 to 4000 ppm, and most preferably 2000 to 3000 ppm. Foaming in a cleaning system typically provides a practical limit for the concentration of fluorinated surfactant in the cleaning solution.

  The washing solution may subsequently be concentrated. Preferably, this is accomplished by passing the wash solution through one or more reverse osmosis (RO) units, with a fluorinated surfactant concentration of 1-35 wt%, more preferably 5-30 wt%, even more preferably 10 Increase to ˜25 wt%, and most preferably 20 ± 5 wt%. The nature of the membrane within the RO unit may require pH adjustment of the cleaning solution for efficient processing. The resulting concentrated wash solution usually has a variety of colors from light brown to brown, which also contains hundreds of ppm of fluoride ions, indicating the inclusion of other impurities such as organic impurities. The hue measured in the APHA hue test described below is typically 50-300.

  Therefore, the recovered concentrated wash solution should preferably be contacted with alumina to reduce the fluoride concentration. This can be done, for example, in a preferred method by passing the concentrated cleaning solution through a layer filled with alumina, or by slurrying the fluorinated surfactant solution with alumina and subsequently separating the solution from the alumina. Can do. This solution is referred to herein as a recovered fluorinated surfactant solution. The temperature of the concentrated cleaning solution during the alumina treatment can be 5 ° C to 90 ° C, preferably 10 ° C to 50 ° C, and more preferably 15 ° C to 30 ° C. The contact time when the alumina layer method is used is in the range of 5 to 60 minutes, although it slightly depends on the temperature. The pH of the concentrated cleaning solution sent to alumina is preferably 4-7, more preferably 5-6.

  The recovered fluorinated surfactant thus obtained may be reused in the polymerization of the fluorinated monomer.

  Alternatively, a concentrated or non-concentrated cleaning solution may be contacted with the adsorbent particles to adsorb the fluorinated surfactant from the cleaning solution. In the context of the present invention, the term “adsorbed particles” means particles that can physically adsorb fluorinated surfactants by any mechanism of physical adsorption, including but not limited to ionic interactions that cause physical adsorption. Therefore, although the adsorption to the exchange resin may occur by a physical adsorption process other than the ion exchange process, the term “adsorbed particles” includes a fluorinated surfactant having an ionic group as a result of the ion exchange process. Also included are ion exchange resins that typically bind the agent.

Suitable adsorbent particles further include activated carbon, silica gel, clay, and zeolite. Preferably used are activated carbon particles. The shape of the adsorbed particles is not particularly important. For example, the adsorbed particles may have a plate shape, may have a spherical shape, a cylindrical shape, or may have a rod shape. Various adsorbed particles having different shapes may be mixed and used. The size of the adsorbed particles is typically 0.05 mm to 20 mm, and generally 0.1 to 10 mm. The practical range is 0.5 to 5 mm. Since adsorbed particles typically adsorb fluorinated acid surfactants on their surface, it will generally be preferable to optimize the specific surface area of the particles, ie the surface area per unit weight. Typically, the specific surface area of the adsorbed particles will be 10 to 5000 m ² / g, generally 100 to 3000 m ² / g, and the practical range will be 300 to 2000 m ² / g.

  Furthermore, anion exchange resin particles can be used as adsorbed particles. Examples of anion exchange resins that can be used to adsorb fluorinated surfactants include strong basic, moderately strong basic, and weakly basic anion exchange resins. The terms strong basic, moderately strong basic and weak basic anion exchange resins are encyclopedia of polymer science and engineering, John Wiley & Sons, 1985, Volume 8, Page 347, and Kirk-Othmer ", John Wiley & Sons, 3rd Edition, Volume 13, page 687. As anion exchange functionality, strongly basic anion exchange resins typically contain quaternary ammonium groups, moderately strong basic resins usually have tertiary amine groups, and weakly basic resins. Usually have a secondary amine. Examples of commercially available anion exchange resins used in the present invention include AMBERLITE® IRA-402, AMBERJET® 4200, AMBERLITE® IRA-67. And AMBERLITE®, IRA-92 (all available from Rohm & Haas), PUROLITE® A845 (Purolite GmbH), and Levachit ( LEWATIT) (registered trademark) MP-500 (Bayer AG).

According to a further embodiment, usable aqueous cleaning liquids have the following general formula:
R ₄ N ⁺ A ⁻
In the formula, each R group independently represents an aliphatic or aromatic hydrocarbon group, and A ⁻ represents an anion. Exemplary R groups include alkyl groups of 1 to 16 carbon atoms, aryl groups of 6 to 10 carbon atoms, or aralkyl groups of 7 to 11 carbon atoms. Typically, the total number of carbon atoms in the R group is at least 15. Typically, the anion is a halide anion such as chloride or bromide, but any other anion may be useful as well.

  Examples of the quaternary ammonium compound of the above formula include, for example, di-n-decyldimethylammonium chloride, hexadecyltrimethylammonium chloride, n-tetradecylbenzyldimethylammonium chloride, n-octyldodecyldimethylammonium chloride and the like. Similar bromides may also be used. Typically, when the exhaust stream contacts a cleaning solution containing an ammonium compound, the ammonium compound will produce an ammonium salt corresponding to the fluorinated surfactant. The ammonium salt of the fluorinated surfactant so produced can then be recovered from the cleaning solution by extraction with an organic solvent, typically a chlorinated solvent. In one embodiment, the extraction step is performed by adding a chlorinated hydrocarbon liquid (liquid at normal room temperature, ie about 22 ° C.). Examples of chlorinated hydrocarbon liquids include, for example, di- or tri-chloromethane. The extraction process may further include a brief stirring at room temperature. The bulk of the quaternary ammonium salt is transferred into the chlorinated hydrocarbon organic layer.

  In further embodiments, the cleaning composition may include adsorbent particles as described above. In this embodiment, therefore, the exhaust stream is in contact with adsorbed particles on which the fluorinated surfactant is adsorbed. In practical embodiments, adsorbent particles include activated carbon particles, polyphenylene oxide (eg, Tenax®), silica, clay, and zeolite. In another embodiment, the adsorbent particles comprise an anion exchange resin. By keeping the anion exchange resin wet, the fluorinated surfactant can be effectively adsorbed on the anion exchange resin.

  Depending on the specific cleaning composition used, sufficient fluorinated surfactants can be recovered from them in various ways and subsequently purified by distillation and / or esterification and reused in the polymerization of fluorinated monomers. The fluorinated surfactant or a salt thereof may be reused in a purified form. In one embodiment, the fluorinated surfactant may be recovered from the cleaning solution by contacting the cleaning solution with adsorbent particles capable of adsorbing the fluorinated surfactant. Suitable adsorbent particles include those described above.

  By eluting the adsorbed particles with an eluent capable of extracting and dissolving the fluorinated surfactant, the fluorinated surfactant adsorbed on the adsorbed particles can be recovered from them. The nature of the eluate typically depends on the nature of the adsorbed particles to which the fluorinated surfactant is adsorbed, and its composition typically includes an organic solvent.

  In one embodiment, the fluorinated surfactant may be recovered from strong, moderately strong, or weakly basic anion exchange resin particles. The terms strong basic, moderately strong basic and weak basic anion exchange resins are encyclopedia of polymer science and engineering, John Wiley & Sons, 1985, Volume 8, Page 347, and Kirk-Othmer ", John Wiley & Sons, 3rd Edition, Volume 13, page 687. As anion exchange functionality, strongly basic anion exchange resins typically contain quaternary ammonium groups, moderately strong basic resins usually have tertiary amine groups, and weakly basic resins. Usually have a secondary amine.

  A suitable eluent for eluting the fluorinated surfactant from the basic anion exchange resin particles includes a mixture of a mineral acid and a water-miscible organic solvent. All suitable mineral acids are anions that impart a salt form on the anion exchanger (anionic form) suitable for further adsorption of the fluorinated surfactant. In general, their oxidative strength should be low so that anion exchangers are not oxidatively damaged under elution conditions. Mineral acids that can be used include, for example, ortho-, meta-, and diphosphoric acid, nitric acid, and preferably hydrochloric acid and sulfuric acid.

  Suitable organic solvents include polar organic solvents such as alcohols, aliphatic or aromatic ethers, nitriles, amides, sulfoxides, ketones, and carboxylic acid esters. Solvents include those that are substantially miscible in water, i.e., can be mixed at least 40% by volume when mixed in equal amounts, or are completely miscible in water. Such solvents include aliphatic alcohols having 1 to 4 carbon atoms, such as methanol and ethanol, and mono- and dimethyl ethers of ethylene glycol and mono- and diethyl ether, or up to the length of decaethylene glycol. And corresponding monoethers of polyglycols having a chain length of Likewise, mixtures of the above-mentioned solvents can be used.

  A typical eluent may be prepared from a mineral acid and an organic solvent, and the acid concentration calculated based on the total mixture may be adjusted to 0.5 to 10N, preferably 0.5 to 2N. In the mixture, the ratio of mineral acid (including water portion) to solvent is in the range of 1: 0.25 to 1:20, preferably 1: 3 to 1:10 parts by volume.

  To quantitatively elute the adsorbed fluorinated surfactant, 50 to 500, and preferably 100 to 225 parts by volume of mineral acid and organic solvent mixture, typically 100 parts of anion exchanger matrix, used.

  When the elution is completed, the eluate is generally separated into two layers, and actually, the lower layer having a high specific gravity contains the entire amount of the fluorinated surfactant. Easily by neutralizing the lower layer with a dilute solution, usually 2N sodium hydroxide solution, allowing the fluorinated surfactant to settle, typically in a small form, and adding the neutralized phase while stirring with dilute hydrochloric acid Can be separated.

  In another embodiment, the elution mixture of the fluorinated surfactant adsorbed on the anion exchange resin is a) water, b) Formula MX (wherein M is an alkali metal or alkylammonium ion, X Is a hydroxyl, fluoride, or chloride) and c) at least one organic solvent capable of dissolving the other components a) and b), thus from the anion exchanger resin to the fluorinated surfactant. A sufficient amount of anion X to elute.

In a particular aspect of this embodiment, the eluate has the following composition:
a) 15-40% water,
b) 1-10 compounds MA, and c) 60-70% solvent.

In another embodiment, the elution mixture has the following composition:
a) 18-35% water,
b) 2-8% MA, and c) 60-70% solvent.

  Useful solvents include those described above. Suitable cations M include lithium, sodium, potassium, tetramethylammonium, and tetraethylammonium, with the preferred anion A being hydroxyl.

In a further embodiment, the fluorinated surfactant may be recovered from the strongly basic anion exchange resin using an eluent comprising an ammonium salt and a water miscible organic solvent. Ammonium salts typically have the following general formula:
(NH ₄ ) _n A
(In the formula, A, OH ^- represents an anion other than, n represents a valence of A) is equivalent to. Examples of anions A include inorganic and organic anions. Specific examples of inorganic anions include, for example, halogens or halogen-containing inorganic anions such as F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ^— , phosphoric acid, sulfuric acid, sulfonic acid, HCO ₃ ⁻ and CO ₃ ²⁻ . Carbonic acid containing is mentioned. Examples of organic anions include, in particular, carboxylic acid anions such as, for example, HCOO ⁻ and CH ₂ COO ⁻ .

  The amount of ammonium salt in the eluate will generally depend on the nature of the anion exchange resin and the amount of fluorinated surfactant adsorbed on the anion exchange resin and / or the desired recovery. Suitable amounts of ammonium salt are generally at least 0.1% by weight. According to a particular embodiment, the amount of ammonium salt is 0.1 to 5% by weight with respect to the total composition used for elution of the exchange resin.

  The elution composition further includes a water miscible solvent. “Water miscible solvent” generally means an organic solvent having a water solubility of at least 5% by weight, such as at least 10% by weight, or at least 20% by weight. Suitable water miscible solvents are typically polar solvents including, for example, alcohols, ketones, ethers, and mixtures thereof. Specific examples of solvents include lower alkanols having 1 to 6 carbon atoms, such as methanol, ethanol, and propanol; glycols, mono- and dialkyl ethers in which the alkyl group has 1 to 4 carbon atoms Or monoglycols and diglycols; ketones such as acetone and methyl ethyl ketone. The amount of the water-miscible organic solvent may vary greatly, but is generally sufficient to dissolve the ammonium salt. The amount of water miscible organic solvent is generally at least 50% by weight of the total amount of the elution composition. A typical range is 50-99.9 wt%, or 60-90 wt%, or 90-98 wt%.

  The eluate containing the ammonium salt and the water miscible solvent may contain additional components that can assist in the recovery of the fluorinated surfactant from the anion exchange resin. In one particular embodiment, the elution composition further comprises water. Water may be used in the elution composition, for example in an amount up to 45% by weight, for example in an amount of 0.1-40% by weight, or in an amount of 1-15% by weight, or in an amount of 4-10% by weight. .

  An additional component that can be present in the eluate is a base. Suitable bases are alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. Other bases that can be used include alkaline earth metal hydroxides, aluminum hydroxide, or alkoxides such as sodium methoxide. When present, the amount of base included in the composition is generally up to 5% by weight. A typical range is 0.1 to 5%, or 0.5 to 2% by weight.

  Other eluents include those disclosed in US Pat. No. 6,642,415 and European Patent 1,323,677. In the latter, an eluate comprising an alkaline mixture of water and an organic solvent is disclosed. An aqueous ammonia solution as disclosed in US Pat. No. 3,882,153 can also be used.

  According to a further embodiment, the fluorinated surfactant may be recovered by mixing adsorbed particles and alcohol, and optionally an acid. The mixture is then generally heated to cause esterification of the fluorinated surfactant in the presence of alcohol so that an ester derivative of the fluorinated surfactant is formed. The mixture thus obtained may then be distilled to form a distillate containing the ester derivative, followed by separation of the ester derivative from the distillate. In general, the eluate will also contain water.

  Suitable alcohols that can be used include, in particular, lower aliphatic alcohols having 1 to 5 carbon atoms, such as methanol, ethanol, and propanol. However, aromatic alcohols can be used as well. Furthermore, the alcohol may be added in the form of an alcohol precursor. However, such precursors will form alcohols under conditions that cause esterification. Suitable alcohol precursors may include adsorbent particles and compounds such as ketals that readily form the corresponding alcohols under acidic conditions in the presence of the eluent or mixtures thereof. The acid used with the eluate is preferably an inorganic acid, but does not exclude the use of organic acids. The acid is preferably a strong acid such as sulfuric acid, hydrochloric acid, phosphoric acid, or nitric acid. The amount and nature of the acid used is typically such that the pH of the eluent and adsorbent particle mixture is less than 4, preferably less than 3, and more preferably less than 2.

  Depending on the amount of water present in the distillate, the ester derivative can be separated from the remainder of the distillate as a separated phase, typically the lower phase. In this way, the ester derivative can be easily separated from the distillate and the remainder of the distillate can be recharged into the mixture to be distilled. Therefore, such a circulation type regeneration process enables easy regeneration of the adsorbed particles with a minimum amount of eluate required. The resulting ester can be further purified by distillation and then converted to the fluorinated acid salt, typically by saponification with ammonia. The eluted and purified fluorinated surfactant salt will typically have sufficient purity to be used as a compound in the emulsion polymerization of fluorinated monomers. If the efficacy drops below an uneconomical level, the adsorbed particles must be discarded, but until then the adsorbed particles can be regenerated several times.

  Of course, the elution method can also be used when the cleaning composition itself contains adsorbed particles.

  After recovery, the fluorinated surfactant can be purified to the desired high purity that enables reuse of the fluorinated surfactant in aqueous emulsion polymerization. A suitable purification method is disclosed in US Pat. No. 5,312,935. Here, the free and dehydrated carboxylic acid is treated with an oxidizing agent such as dichromate, peroxodisulfate, or permanganate at a temperature from about 60 ° C. to the boiling point of the mixture. The pure product is then separated, for example by crystallization at low temperature, or preferably by distillation if vacuum is desired. Or you may use the method of PCT international publication patent WO2004 / 031141.

Embodiments of the present invention also include aqueous compositions. In some embodiments, the aqueous composition has the general formula:
[R _f ¹ —O— (CF ₂ ) _n —CO ₂ ⁻ ] _i M ^{i +}
Wherein R _f ¹ is CF ₃ CFH, n is an integer selected from 1 to 6, M is a cation having a valence i, and i is selected from 1, 2, and 3. A partially fluorinated surfactant. In another embodiment, the aqueous composition has the general formula:
[R _f ² —O— (CF ₂ ) _m —CO ₂ ⁻ ] _i M ^{i +}
Wherein R _f ² is CF ₃ CF ₂ , m is an integer selected from 1, 3, 4, 5, and 6, M is a cation having a valence i, and i is 1 2) and a fully fluorinated ethyl ether surfactant. In yet additional embodiments, the aqueous composition has the general formula:
[R _f ³ —O— (CF ₂ ) _p —CO ₂ ⁻ ] _i M ^{i +}
Wherein R _f ³ is CF ₃ (CF ₂ ) ₃ , p is an integer selected from 1, 4, and 6, M is a cation having a valence i, and i is 1, 2) and a fully fluorinated butyl ether surfactant. The aqueous composition may also contain any mixture of the fluorinated surfactants described above.

  The aqueous composition may be present, for example, in the form of an aqueous dispersion of a fluoropolymer. The fluoropolymer particles in the aqueous dispersion may have a Z-average particle size of, for example, 40 nm or more, 50 nm or more, 100 nm or more, and further 200 nm or more. The Z-average particle size of the fluoropolymer particles further has a Z-average particle size of, for example, up to 400 nm, up to 300 nm, up to 200 nm, and even up to 100 nm.

  In some embodiments, the fluoropolymer particle amount is from 5 to 70% by weight based on the total weight of the composition. A high solid concentration may be obtained by concentrating the dispersion obtained by emulsion polymerization. In another embodiment, the fluoropolymer particle amount may be 5% by weight or more, 10% by weight or more, 20% by weight or more, and further 50% by weight or more based on the total weight of the composition. In further additional embodiments, the amount of fluoropolymer particles may be up to 70%, up to 60%, up to 50%, or even up to 40% by weight relative to the total weight of the composition.

  In further additional embodiments, the aqueous composition may further comprise a non-ionic, non-fluorinated surfactant. These nonionic surfactants are described below as “stabilizing surfactants”.

In order to obtain fluoropolymer dispersions suitable for use in the manufacture of layered articles, such as, for example, impregnated fabrics or coatings of metal substrates, for example for the production of cooking utensils, generally a stabilizing interface It is desirable to further add the activator to the fluoropolymer dispersion. Typically, such stabilizing surfactants can be added in an amount of 1-12% by weight, based on the solid weight of the fluoropolymer. Examples of nonionic surfactants that can be added include the following general formula:
^{_{R 1 -O- [CH 2 CH 2}} O] n - [R 2 O] m -R 3
In which R ¹ represents an aromatic or aliphatic hydrocarbon group having at least 8 carbon atoms, R ² represents an alkylene having 3 carbon atoms, R ³ Represents hydrogen or a C1-C3 alkyl group, n has a value of 0-40, m has a value of 0-40, and the sum of n + m is at least 2.

  It will be appreciated that in the general formula for nonionic surfactants, the units represented by n and m may appear as blocks or may exist in an alternating or random structure. Examples of nonionic surfactants according to the above general formula include alkylphenol oxyethylates, such as ethoxylated p-isooctylphenol, wherein the number of ethoxy units is 15, 10, 8, 7, or even 5.

Further examples of nonionic surfactants of the general formula include those in which R ¹ represents an alkyl group of 4 to 20 carbon atoms, m is 0, and R ³ is hydrogen. Examples of these include isotridecanol ethoxylated with about 8 ethoxy groups. Nonionic surfactants according to the general formula, where the hydrophilic moiety comprises a block copolymer of ethoxy groups and propoxy groups, may be used as well.

  Therefore, embodiments of the present invention also include a method for producing a layered article and a layered article produced by the method described. Such a layered article may be produced, for example, by a coating method. For coating applications, when an aqueous dispersion of fluoropolymer and a surfactant are desired, it is not necessary to separate or solidify the fluoropolymer from the dispersion. Examples of surfactants suitable for aqueous dispersions in the method for producing layered articles include those described above as useful for preparing aqueous compositions according to the present application.

  The advantages and embodiments of the present invention are further illustrated by the following examples, wherein the specific materials and their amounts listed in these examples, as well as other conditions and details, shall unduly limit the present invention. Should not be interpreted. All parts and proportions are by weight unless otherwise specified.

Test method:
Latex particle size measurements were performed using dynamic light scattering with a Malvern Zetazizer 1000 HAS according to ISO / DIS 13321. Before the measurement, the polymer latex obtained by polymerization was diluted with a 0.001 mol / L KCl solution. In all cases, the measurement temperature was 25 ° C. The reported average value is the Z-average particle size.

SSG: Standard specific gravity was measured according to ASTM 4894-04.
Solid content: Determination of the solid content was done by exposing the latex sample to temperatures up to 250 ° C. for 30 minutes.

Comparative Example C1: CF ₃ (CF ₂ ) ₆ COONH ₄
Linear material prepared from TFE telomer.

Comparative Example C2:

_{CF 3 CF 2 CF 2 OCF (} CF 3) a _{CF 2 OCF = CF 2, CF} 3 CF 2 CF 2 OCF (CF 3) CF 2 OCF 2 COOCH 3 ( boiling point 91-92 ° C. at 13.3kPa (133mbar)) Was performed as described in US Pat. No. 4,987,254. The ester was reacted with aqueous ammonia and methanol was removed by distillation to produce CF ₃ CF ₂ CF ₂ OCF (CF ₃ ) CF ₂ OCF ₂ COONH ₄ . All structures were confirmed by F-NMR spectra. Depending on the isomer content in the vinyl ether, isomers having the structure CF ₃ CF ₂ CF ₂ OCF ₂ CF (CF ₃ ) OCF ₂ COOX (X═CH ₃ , NH ₄ ) were also detected.

(Example _{1): C 4 F 9 -O} -CF 2 -CF 2 -COONH 4
Example 1 was synthesized by reaction of perfluorobutyric fluoride with tetrafluorooxetane and fluorination of the CH ₂ group prior to conversion to the ammonium salt as described in PCT International Publication No. WO 2005/003075.

Example 2 CF ₃ —CFH—O— (CF ₂ ) ₃ COONH ₄
Sample of dibasic acid fluoride, FCOCF (CF ₃ ) —O— (CF ₂ ) ₃ COF, prepared by HFPO coupling of perfluorosuccinyl fluoride (503 g, 1.4 mol) (US Patent Publication No. 2004/0116742) Was added to a stirred sodium carbonate (387 g, 3.7 mol) / diglyme 650 g slurry at 78 ° C. over 2 hours to produce the di-salt. This reaction liberated CO ₂ gas. Distilled water (35 g, 1.9 mol) was added at 85 ° C. While discharging CO ₂ gas, the mixture was heated to 165 ° C. and maintained for 30 minutes. The reaction mixture was cooled and sulfuric acid (250 g, 2.6 mol) / water 1250 g was added to acidify the reaction mixture. NaOH 60 g / water 60 g was added to the lower phase. The salt was dried in a vacuum oven at 112 ° C./2×103 Pa (15 mmHg), and 450 g was recovered. 300 g of 50% sulfuric acid was added to the salt, and the lower fluorochemical phase was washed once with 200 g of 50% sulfuric acid. By vacuum distillation, CF ₃ —CFH—O— (CF ₂ ) ₃ COOH (400 g, 1.3 mol) having a boiling point of 111 ° C./2×10 ³ Pa (15 mmHg) was obtained in a yield of 95%. The acid was treated with caustic, followed by sulfuric acid treatment and vacuum distillation. This was repeated twice to obtain a colorless acid. All structures were confirmed by ¹ H and ¹⁹ F NMR. A surfactant having a melting point of 64-68 ° C., CF ₃ —CFH—O— (CF ₂ ) ₃ COO—NH _4, was quantitatively obtained by reaction of 208 g of acid with excess ammonium hydroxide and drying. .

Example 3 CF ₃ —CFH—O— (CF ₂ ) ₅ COONH ₄
Sample (500 g, 1.1 mol) of dibasic acid fluoride, FCOCF (CF ₃ ) —O— (CF ₂ ) ₅ COF, prepared by hexafluoropropylene oxide (HFPO) coupling of perfluoroadipoyl fluoride ( US Patent Publication No. 2004/0116742) is added to a stirred sodium carbonate (500 g, 4.7 mol) / diglyme 500 g slurry at 85 ° C. over 2 hours to form a di-salt did. This reaction liberated CO ₂ gas. Distilled water (25 g, 1.4 mol) was added at 85 ° C. While discharging CO ₂ gas, the mixture was heated to 168 ° C. and maintained for 30 minutes. The reaction mixture was cooled and sulfuric acid (350 g, 3.6 mol) / 1100 g of water was added to acidify the reaction mixture. The lower phase is washed with 400 g of 50% sulfuric acid, and vacuum distillation yields CF ₃ —CFH—O— (CF ₂ ) ₅ COOH (426 g, 1.0 mol) having a boiling point of 132-135 ° C./15 mm. Obtained at 95%. Subsequently, 46 g NaOH / 63 g water was added. The salt was dried in a vacuum oven at 112 ° C./2×10 ³ Pa (15 mmHg) to obtain 386 g of a pale yellow sticky solid. Sulfuric acid was added to the salt and the lower fluorochemical phase was vacuum distilled. The process was repeated twice more to give a colorless acid. All structures were confirmed by ¹ H and ¹⁹ F NMR. A surfactant having a melting point of 159 to 165 ° C., CF ₃ —CFH—O— (CF ₂ ) ₅ COONH ₄ is quantitatively obtained by reaction with 200 g of acid reacted with excess ammonium hydroxide and drying. It was.

(Example _{4): CF 3 -CF 2 -O-} (CF 2) 5 COONH 4
291 g of freshly distilled FOCCF (CF ₃ ) O (CF ₂ ) ₅ COF was placed in a glass flask equipped with a magnetic stirrer, a thermometer, an external heating device, a reflux condenser, and a dropping funnel. 50.9 g SbF ₅ was added at room temperature. The start of the reaction was indicated by the slow evolution of gas. The batch was heated to 70 ° C. until no more gas was generated. The IR spectrum of the exhaust gas clearly showed the generation of carbon monoxide. Methanol was added and the resulting crude ester was washed three times with water. The lower ester phase was separated (334 g) and analyzed by GC to find C ₂ F ₅ O (CF ₂ ) ₅ COOCH ₃ (44 area%) and CH ₃ OOCFCCF ₃ O (CF ₂ ) ₅ COOCH ₃ (48 area%) The presence of was shown. Distillation of the crude ester yielded 85.5 g of C ₂ F ₅ O (CF ₂ ) ₅ COOCH ₃ (boiling point 46 ° C./1×10 ³ Pa (7.5 mmHg)), with an isolated yield of 32. Equivalent to 4% 80 g of the distilled ester was converted to the ammonium salt by heating with aqueous ammonia, the methanol formed was removed from the aqueous phase by distillation, and this aqueous ammonium salt solution was used as an emulsifier for fluoropolymer polymerization. All structures were confirmed by F-NMR spectra.

Measurement of bioaccumulation Urinary clearance of fully fluorinated and partially fluorinated carboxylates was evaluated in a pharmacokinetic study in rats. The objective was to assess the rate of excretion by measuring the total amount of parent compound excreted via urine excretion. This study was approved by IACUC ^* and was conducted at a 3M Company AAALAC ^** certified facility.

  In this study, male Sprague Dawley rats 6-8 weeks old and weighing approximately 200-250 g were used at the start of the study. Test compounds in Table 2 were administered to rats (number of animals per test compound N = 3) at a dose of 73 micromole per kg body weight. All test compounds were prepared in sterile deionized water and given to rats by oral gavage. After administration of test compounds, rats were individually housed in metabolic cages for urine collection: 0-6 hours, 6-24 hours, 24-48 hours, and 72-96 hours. Animals were observed throughout the study for clinical signs of toxicity. At the end of each study (96 hours after administration), gross necropsy was performed and serum and liver samples from each animal were preserved.

  The concentrations of the parent compounds or their metabolites were quantitatively measured by fluorine NMR for each urine sample at each time point for each animal with reference to the internally added standard.

The bioaccumulation data obtained according to the above test is reported in Table 2.
^* IACUC: Institutional Animal Care and Use Committees
^** AAALAC: Association for Assessment and Accreditation of Laboratory Animal Care

In Table 2, T _1/2 is required for the amount of a specific substance in a biological system to be reduced to one-half of its value by a biological process when the removal rate is approximately exponential. It is time to In these examples, the value of T _1/2 is calculated by an exponential least square curve fitting method (y = Ae ^Bx and T _1/2 = 0.693 / B), where y is the urine value Represents the concentration of the target substance in it, and x represents time (hours).

Polymerization Overview Polymerization experiments were conducted in a 40 L kettle equipped with an impeller stirrer and baffle. 30 L of deionized water was added to the kettle and set to 35 ° C. The kettle was repeatedly evacuated to remove oxygen and the stirring speed was set to 165 rpm. A 70 mmol fluorinated emulsifier listed in Table 3 was placed in an oxygen free kettle (unless otherwise specified) and the following materials were added: 40 mg copper sulfate pentahydrate and 1 mg concentrated sulfuric acid. 0.5 mL solution; 15 g of 25 wt% aqueous ammonia and 5.6 g PPVE-2 (synthesized by trimerization of HFPO, conversion of oxyfluoride to alkali salt, and pyrolysis of dry salt (German application (Angew. Chem., 24, 161-179, 1985) Finally, the reactor was pressurized to 0.2 MPa with TFE and 47 g of HFP was added, and the kettle was then added using TFE. 100 mL of an aqueous initiator solution set to 1.5 MPa and containing 140 mg of sodium disulfite, then 100 m of a solution containing 340 mg of ammonium peroxodisulfate Was pumped into the reactor, the beginning of the polymerization was indicated by a pressure drop, during which the pressure was maintained at 1.5 MPa by continuously feeding TFE, after adding 3.2 kg of TFE, The monomer valve was closed and the pressure was released, and the characteristics of the resulting polymer latex are summarized in Table 3.

1000 mL of this polymer dispersion was coagulated by adding 20 mL of hydrochloric acid while stirring. The coagulated material was agglomerated with gasoline and washed repeatedly. The agglomerated polymer was dried in a vacuum oven at 200 ° C. overnight; test data is shown in Table 3.

  It will be understood by those skilled in the art that various modifications and variations of the present invention can be made without departing from the scope and spirit of the invention, but the invention is not unduly limited to the embodiments shown. Should.

Claims (5)

The following general formula:
^{_{[R f 1 -O- (CF 2}} ) n -CO 2 -] i M i +
(Wherein R _f ¹ is CF ₃ CFH, n is 1, M is a cation having a valence i, and i is selected from 1, 2, and 3) containing fluorinated surfactant or we selected the fluorinated ether carboxylic acid or acid derivative, emulsion polymerization surfactant.   The surfactant according to claim 1, wherein the surfactant has a renal excretion half-life in male rats of 35 hours or less.   The surfactant according to claim 1, wherein the surfactant does not undergo metabolic degradation, and a recovery rate by renal excretion in male rats after 96 hours of administration is 30% or more.   An aqueous composition comprising the fluorinated surfactant according to claim 1. A process for preparing a fluoropolymer dispersion comprising the step of polymerizing one or more fluorinated monomers in an aqueous emulsion comprising:
The polymerization step is carried out in the presence of one or more fluorinated surfactants according to claim 1;
Method.